Telephone system.



O. D. M. GU THE,

TELEPHONE SYSTEM.

APPLICATION man AUG. 20. 1911.

Patented Apr. 30, 1918.

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O. D. M. GUTHE.

TELEPHONE SYSTEM. APPLICATION FI'LED AUG.20, 19w.

1,264,388. Patented Apr. 30, 1918.

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To all whom it may concern:

UNITED STATES PATENT OFFICE.

01.01 D. in. GUTHE, 01 EAST ORANGE, NEw JERSEY, ASSIGNOR. To WESTERN ELEcTEIc COMPANY, INCORPORATED, 01 NEW YORK, N. Y., A CORPORATION OF NEw YORK.

TELEPHONE SYSTEM.

7 Be it known that I, OLOF D. GUTHE, a citizen of the United States, residlng at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone Systems,

of which the following is a full, clear, concise, and exact description;

the group. find all trun This invention relates to telephone systems employing machine switching.

It frequentl happens that, due to a large number of calL occurring simultaneously 1n a given group of lines, a selector switch attempting to extend a calling line into a particular level or group of trunks will find them all busy. In this case the brushes after having moved over the last set of trunk terminals and found them busy, remain in their actuated position until the calling party hangs up his receiver to establish a release circuit. In the meant me, and while the calling subscriber is awaiting 1' sponse, one or more trunks of the group tested by the. selector during its secondary movement ma have become idle but this avails himnothing.

It is then one of the principal ob ects of this invention to provide a selector switch which is so constructed and arranged that its hunting movement is continuou both 7 forth and back over the terminals of a selector groupythat is, if the selector brushes during their first searchln movement over busy, certain changes are thereupon effected to cause said brushes to start back over the group, testing each one, and to seize the first idle one that is reached. If no idle trunk is found during the return movement certain changes will be brought about to cause the brushes to start out upon another excursion. This continuous hunting movement will not cease until an idle trunk has been seized or until the calling party abandons the call'by hanging up his receiver. I

This object is attained by employing a switch in whichthe brush shaft is actuated by a stepping magnet to move its brushes over terminals in one direction, and then after having reached the last terminal,

through the agency of certain mechanical This and other objects contemplated by Specification of Letters Patent. I Patented Apr. 30, 1918 Application filed August 20, 1917. Serial No. 187,226.

the present invention will become apparent to those skilled in the art from a considera:

tion of the following description, taken together with the accompanying drawings wherein:

Figure l is a diagrammatic representation of one type of selector switch embodying the features of this invention, together with a portion of the circuit arrangement of a telephone system. In this type of switch, the construction is such that a rotary movement is first given the brush shaft to position a set ofbrushes in operative relation to a desired group, and thereafter a, vertical motion is given the shaft to wipe its brushes over the trunk terminals.

Fig. 2 is a showing somewhat similar to Fig. 1, illustrating the application of the invention to a switch of the up-and-around class wherein the primary or grou selecting movement actuates the brush sha t in ,a vertical direction, and the secondary or trunk selector switch in connectlon with its associated circuits and elements.

With reference to F ig, 1, upon the subscriber at substation A removing his receiver to initiate a call, the closure of his circuit at the switchhook causes a line finder F to move its brushes 5, b, b automatically into engagement with the terminals 25,- t' t of the calling line. This extends the line through to the'first selector switch FS, closing a circuit for the line relay 100, which circuit may be traced from the free pole of battery, righthand winding of relay 100, side-switch arm 101 in its first position, trunk conductor T, wiper b and terminal t of finder F, through the telephone loop of substation A, terminal 1 t and wiper 12, trunk conductor T, sideswitch arm 102 in its first position, through the left-hand winding of relay 100 to ground-' 7 ed battery. Relay 100, upon energizing, at-

tracts its armature and closes a circuit for the slow release relay 103 extending from free pole of battery, winding of such relay a second slow release relay 104, and also for 103, the front contact and armature of relay 100 to ound. At its armature and front contact, the relay 103 prepares a circuit for the rimary magnet PM of selector FS.

The subscriber at station A by operating a sender S sends a series of impulses over the line in accordance with the first digit of the called number, thus causing relay 100 to vibrate its armature correspondingly. At the first retraction, said relay closes a circuit for the primary magnet PM from. ground, armature and back contact of the relay 100, armature and front contact of relay 103, conductor 105, secondary off-normal contact SON, magnet PM to battery and ground. The armature 106 of this magnet 1s pivoted at 107 and at its other end 18 provided with a stepping pawl 108, whlch is adapted, upon each attraction of the armature, to engage a ratchet wheel 109 to rotate the same through an angular distance corresponding to one tooth. The ratchet 109 is splined upon a brush shaft 110 so that the shaft is constrained to rotate therewlth but may moveindependently thereof in a longitudinal direction. Fixed to the upper portion of shaft 110 are sets of brushes B,

arranged in a spiral fashion about theshaftand normally in a plane just below the groups ofterminals T with which they cooperate. Thus at each retraction of the line relay 100 and the resulting energization of magnet PM over the circuit traced, the shaft 110 is rotated one step to bring a particular set of brushes B in operative relation to its trunk group. .Atthe same time, the relay 100 on retracting its armature for the first time closed a circuit for relay 104, traceable from battery, relay 104, front contact and armature of relay 103, back contact and armature of relay 100 to ground. Relay 104 upon energizing establishes a circuit for the escape magnet 111 as follows: battery, magnet 111, side-switch arm 112 in its first position, armature and contact of relay 104 to ground. Relay 104 is slow to release and thereby holds its contact closed duringthe transmission of each series of impulses. The escape magnet which controls the side switch is designed to step such switch from first to second position upon its deenergization.

At the termination of the first series of impulses the circuit for relay 100 is maintained closed and thereby holds its armature attracted for a sufiicient period to permit the slow release relay 104 to denergize and retract its armature and open the escape magnet circuit. Upon deenergizing, the es cape magnet 111 passes the side switch into its'second position, and at the arm 113 completes a circuit for the secondary stepping magnet SM as follows: battery, interrupter springs 114, winding of magnet SM, conductor 115, side-switch arm 113 in its second position, front contact and-armature of relay 100 to ground. The magnet SM is provided with an armature 11 6 pivoted. at 117, and having fixed to its free end a spring pressed pawl 118. At each actuation of the armature 116, said pawl is adapted to engage a vertical ratchet 119 to elevate the shaft 110 to move the brushes B over the selected set of trunk terminals. When armature 116 is retracted, an arm 120 of pawl 118 rests on a stop 121 to hold the pawl away from the ratchet teeth. This arm 120 serves for a further purpose as will be seen hereinafter. As seen, the interrupter springs 114 are controlled by armature 116 so that for each time the magnet SM energizes and attracts its armature to raise the brush shaft 110one step, the springs 114 are separated to open the circuit. In this mannerthe magnet SM interrupts itsown circuit and elevates the shaft 110 step by step, wiping the brushes -B over the terminals T in search of an idle trunk. We will assume that idle .trunks are those upon whose test terminals a ground potential is present. If then, aset of brushes B, as for instance, the set 122, 123 and 124, having been first rotated by magnet PM into operative relation with its trunk group, and upon its secondary vertical movement comes in contact with an idle set of terminals such as the second set 125, 126 and 127, a ground will be found 'upon test terminal 126 of said set. 'A circuit is now established for the escape magnet 111 from free pole of battery, winding of 111,

side-switch arm 112 in its second position,

test wire 128, test wipers 124, to the ground: ed terminal 126. The escape magnet 'is so constructed as to move the side switch from second to third position upon energization. The side'switch'upon passing to third position opens the circuit for magnet SM to stop the brushes 0n the selected terminals, and by means of arms 101 and 102 the calling line is extended over conductors 129 and 130 to Wipers 122, 123 and thence over the selected trunk to the next switch.

At the end of the conversation when the receivers are replaced, a round is applied to the test Wire. 128 and t e release magnet RM is energized over the following circuits: battery, magnet RM, primary off-normal springs 131, which closed at the first rotary step, sideswitch arm 132 in its third position, to the grounded test Wire 128. The release magnet by energizing operates to restore the switch to normal in the well-known manner.

If, however, the set of brushes B in their secondary hunting movement had failed to find an idle set of trunks, means including the construction of the selector switch itself are provided whereby the brushes, after having tested the entire group of terminals, are thereupon moved pack over the group in the opposite'direction to again test for an idle trunk. Considerin the structure of the selector more particlfiarly, there is seen to be a pair of levers 133 and 134 ivotally attached to a block 135 by means of a screw 136. Said block is slidably mounted upon a stationary guide and support 137 so as to be movable to and awa from the brush shaft A 110. Toward their ree ends the levers 133 and 134 are shaped to present a pair of shoulders 138 which are adapted to engage the teeth of-vertical ratchet 119 as will res ently be described. A spring 139 ten s to hold the levers 133 and 134 together resiliently. A second spring 140 acts to hold the block 135 and its'associated levers in their normal positions away from ratchet 119. A bell-crank lever pivoted at 141 has one of its arms 142 extending laterally toward shaft 110. The other arm 143 projects downwardly and has a slotted engagement with the block 135. At the extreme upper and lower ends the vertical ratchet is constructed to provide two oppositely disposed cone shaped members 144 and 145, both of which are somewhat larger in diameter than the ratchet teeth 119. A lever 146 pivoted at 147 has a cam 148 and a projecting finger 149, the purpose of which will be later explained. The levers 133 and 134 are each given an angular off-set near their pivoted ends; that is, the lever 133 is bent upwardly as shown at 150, whereas the lever 134 is bent oppositely and downwardly. This brings the shoulders 138 in different planes so that only one will be in engagement with a ratchet tooth 119 at a time. The free ends of levers 133 and 134 are shaped to present respectively the inclined plane surfaces 151 and 152 which are adapted to coiiperate with a roller 153 mounted on armature 116.

Pivotally attached to a spindle 154 aretwo holding dogs 155 and 156 coiiperating respectively with the rotary and vertical ratchets 109 and 119 to maintain the shaft 110 in position. Dog 155 is controlled by release ma et RM to withdraw from ratchet 109 and also has a finger 157 arranged to engage a finger 158 to force the vertical holding dog 1 56 away from its ratchet whenever the release magnet is energized. But the vertical holding dog 156 may be actuated independently of the dog 155. A lug on dog 156 is provided with a notch 159 which is adapted to be engaged by a cam dog 160 on the lever 143.

Coming to the operation, and assuming that on the first upward motion' of the brushes B all trunks were found busy, the enlarged member 144 will, after the shaft 110 has taken its last vertical step, encounter the lever 142 and thereby move the block 135 and its attached levers 133, 134, toward the shaft 110 until one of the shoulders 138 is in holding relation with the last ratchet tooth 119. At the same time the inclined surfaces 151, 152 have moved into working relation with rollers 153, and the cam do 160 has forced the vertical holding paw away from the ratchet and also looked itself into notch 159, thereby holding levers 133, 134 against the tension of spring 140. The armature 116 on retracting causes pawl 118 to contact the enlarged-member 145 which tilts the lever 120 upward sufliciently to permit finger 149 to move in between said lever 120 and the stop 121. This prevents pawl 118 the rol1er'153 to alternately engage cams- 151 and 152. For each energization of said 4 magnet the escapement levers 133, 134 permit the brush shaft to descend one step, allowing brushes B to test the terminals of the group. If an idle set is found the circuit of magnet SM is broken in the manner already described. If, on the return hunting movement all trunks are busy, when the last step is taken member 144 engages the nose of vertical holding dog 156 to force it still farther away from the shaft 110. This permits dog 160 to unlock from notch 159, and spring 140now withdraws escapement levers 133, 134 away from ratchet 119. -At the same time member 144 engages the cam 148 of lever 146 to force the finger 149 out from under lever 120. The brush shaft is now under the control of pawl 118 and dog 156 and again starts out on another hunting movement in the manner described. Such continuous operation will obtain until an idle trunk is located or until the party at A hangs up his receiver. In the latter case the release magnet is energized over a circuit extending from battery, winding of RM, off-normal springs 131, arm 132 in its second position, back contacts and armatures of relays 103 and 100 to ground. On at Fig. 2, when the receiver at substation A is removed to initiate a call the line circuit is extended by means of a finder F to the first selector switch IT'S. A circuit is thereby closed for line relay 200 over side-switch wipers 201, 202, in their first position, wipers .and terminals of finder F and the telephone apparatus at station A. Relay 200 on pullin u closes a circuit for slow release rela g P V 203, which by attracting its armature prepares a circuit for prlmary magnet PM' and also places a break in the circuit of release magnet 'RM. The subscriber now operating his sender S transmits a series of impulses in accordance wlth the first digit, thereby vibrating the armature of relay 200. At each retraction of such relay the magnet PM is energized .over a circuit leading through the front contact and armature of slow release relay 203, back contact and ar mature of relay 200 to ground. At each actuation of armature 204 the pawl 205 engages the ratchet 206 on brush shaft 207 of the selector to elevate distance of one tooth. The shaft 207 has fixed to its upper end a set of talking brushes B and a test brush B adapted to wipe over their corresponding terminal banks. The lower end of shaft 207 is fitted in a hollow shaft 208 so as to be rotatable therewith but movable independently thereof in an axial direction. Thus the first series of impulses causes the magnet P M to vibrate its armature to step the brushes B, B vertically into operative relation with a particular horizontal row of trunkterminals. When relay 200 first released at the beginning of the impulse series it closed a circuit for slow release relay 209, which on pulling up established a circuit for escapement magnet 210, in the manner described in connection with Fig. 1. At the end of the series the magnet 210 deenergizes to step the side switch to its second position, completing a circuit for the secondary magnet SM from. free pole of battery, magnet SM, interrupter springs 211, side-switch arm 212, in second position, to ground at the front contact and armature of 200. The secondary magnet S'M rotates the brush shaft step by step, interrupting its own circuit at springs 211, to wipe the brushes over the terminals of the group in search of an idle one thereof. As soon as an idle trunk is found, which has its test terminal grounded, the escape magnet 210 becomes energized and by advancing the side switch cuts out the secondary magnet and also extends the calling line through to the next switch.

The specific construction and manner in which continuous trunk hunting is obtained in a switch of this type will now be considered. The hollow shaft 208 has securely fastened thereon a pair of ratchet wheels 213, 214, inverted with respect ,to each other so that their teeth are oppositely disposed.

, Pivoted to the frame of the magnet SM' is an armature 215. Also hinged to the same spindle 216 is a supplementary member 217 which is attached by means of a screw 218 to vibrate with armature 215, but which is also capable of vertical movement on the spindle 216. A bell-crank lever rotatably fastened to the member 217 has one arm 219 said shaft through the extending to co-act with a pair of springs.

220, 221, and on its other arm 222 carries a pair of pawls 223 and 224:, adapted to extend so as to be capable of engagin the ratchets 213 and 21 1 respectively. on the supplementar member 217 is in the pa sition shown in t e figure the pawl 223. lies in substantially the same plane as ratchet viewed from above, through the distance ofone tooth. On the other hand, when member 217 has been raised to its upper position, as will presently be seen, pawl 224 is brought into operative relation with ratchet 214 and spring 221 forces it into engagement therewith when-the armature 215 is actuated to rotate the brush shaft in a counter-clockwise direction. A disk 226 fastened to shaft 208 has two cut-away portions 227, 228, in which are arranged, as shown the springs 229 and 230. A lever 231 is plvoted to the frame of the switch as at 232 and has one end projecting to cooperate with the springs and notches of disk 226. The other end connects with spindle 216. Below disk 226 and also secured on shaft 208 is a notched disk 233. The vertical and rotary holding dogs 234: and 235 are mounted on the rod 236 under the control of release magnet RM. The dog 235 includes a roller 237 which is normally held in contact with the notched periphery of disk 233 by spring 238. Fingers 239 and 2 10 are so arranged that the roller 237 may ride upon the fluted surface of disk 233 without retracting dog 234 from engagement with the vertical ratchet 206, yet when magnet RM energizes both holding dogs are withdrawn.

The operation is as follows: Assuming the first digit has been sent, operating the primary magnet P M to elevate shaft 207 to position the brushes B, B opposite a given row of trunk terminals, the side switch thereupon moves to second position closing a circuit for secondary magnet S which interrupts its ,own circuit at each vibration of its armature as before mentioned. At each attraction of the armature the pawl 223 engages the ratchet 213 to move the shaft 207 through the distance corresponding to one set of terminals. The roller 237 of holding dog 235 likewise engages each successive notch in disk 233 and holds the same with suificient force to prevent spring 241 from restoring the shaft. This operation continues, the brushes B, B passing from one terminal to another until the test brush B encounters an idle trunk, whereby the escape magnet is energized and operates to break the circuit of the stepping magnet, bringing the switch to rest. While the brush shaft is thus bein rotated in a clockwise direction the end 0 lever 231 rests on the upper surface of the disk 226. If, during the hunting movement of the brushes, all trunks are found to be busy, when the last set is reached the disk 226 will have rotated'so that the free end of s ring 230 passes over the end of lever 231 an forces it down through the notch 228 to the under side of said disk. Such motion of lever 231 about its fulcrum 232 raises the supplementary member 217, thereby elevating the lever 222 to bring the lever 224 into working relation with ratchet 214, and the lever 219 under the pressure of spring 221. Operation of the secondar magnet now serves to rotate the brush sha step by step in a counter-clockwise direction, its brushes testing each set of terminals as in the forward movement. If no idle trunk is found during the return movement the spring 229 passes under lever 231 and forces it back to the position shown in the drawing. This causes the control of the brush shaft to be shifted back to the pawl 223, which proceeds to again rotate said shaft as before. Hunting movement will continue until an idle trunk is found or until the party at A hangs up his receiver to close a release circuit.

In both embodiments of the invention as shown in Figs. 1 and 2, when a release circuit i established and the release magnet energizes, a complete restoration of the switch to its normal position occurs whether the trunk engaged was seized by the wipers either on forward or backward movement or whether said wipers are at the time in the process of hunting an idle trunk.

It will be obvious to others skilled in the art thatvarious changes and alterations may be made and it will therefore, be understood that I do not wish to be limited to the exact details of construction and arrangement shown.

What is claimed is:

1. In a telephone system, in combination, telephone lines, an automatic switch, means for associating said lines with the automatic switch, trunk oups terminating in said switch, means or moving said switch into operatlve relation with one of said groups, a stepping magnet with means for operating the same to continuously move the switch forth and back over said group, and means effective to stop the motion of the switch when an idle trunk is found.

2. In a telephone system, in combination, telephone lines, an automatic switch, means for associating said lines with the automatic switch, trunk groups terminating in said switch, means to position said switch in operative relation with one of said groups of contacts, an electro-magnet, means for operatingsaid magnet to move the switch over said switch, trunk groups terminating in I contacts in said switc'h, an electro-magnet adapted to continuously move said switch both forth and back over a group of said contacts, means effective when said switch is moving in either direction for causing it to seize the first idle trunk encountered, and means for restoring said switch to normal position after having been operated in either direction to seize an idle trunk.

4. In a telephone system, in combination, telephone lines, a selector, means for associating said lines therewith, trunks terminating in groups in said selector, a brush shaft for said selector, a primary and a secondary magnet, means to operate the primary magnet to position a set of'brushes in operative relation with one of said groups, means to operate the secondary magnet to move said set of brushes over the group to test for an idle trunk therein, means efi'ective if no idle trunk is found whereby when the last trunk has been tested the secondary magnet, continuing to operate, moves the brushes in the opposite direction over said group to search for an idle trunk, and means operative when the brushes are moving in either direction for stopping the same upon the contacts of the first idle trunk encountered.

5. In a telephone system, telephone lines, trunks terminating in groups of fixed contacts, a selector switch for extending said lines to said trunks having a brush shaft with brushes therefor, a rotary and a vertical magnet, means for operating the rotary magnet to position a set of brushes in operative relation with one of said groups of contacts, means for energizing the vertical magnet, an armature responsive thereto,.a vertical stepping pawl actuated by said armature to step said shaft with its positioned set of brushes over said group of contacts, a vertical holding pawl to maintain the shaft in its operated position, means actuated to render said stepping and holding 'pawls ineffective when the brushes have reached the end of the group, and means for thereupon assum-' ing control of said shaft, said last mentioned means being actuated by the vertical magnet to step said shaft with its brushes in the opposite direction over said contact group.

6. In a telephone system, telephone lines, trunks terminating in groups of fixed contacts, a selector switch for extendingsaid lines'to said trunks,.said selector having a brush shaft with brushes therefor, a rotary and a vertical magnet, means for operating the rotary magnet to position a set 0 brushes in operative relation with one of said groups of contacts, energizing means for the vertical magnet, an armature responsive thereto, a vertical stepping pawl actuated by said armature to step said shaft with its positioned set of brushes over said group of contacts, a vertical holding pawl to maintain the shaft in its operated position, means actuated to render said stepping and holding Eawls ineflective when the brushes have reac ed the end of the group, means for I thereupon assuming control of said shaft,

said last mentioned means being actuated by the vertical magnet to step said shaft with its brushes in the opposite direction over said contact roup, and means actuated when the brus es have returned to the beginning of thegroup to shift the control of said shaft back to the vertical stepping and holding pawls whereby the brushes are again moved over said. group of contacts.

7. In a telephone system, telephone lines, trunks terminating in groups of fixed con tacts, a selector switch for extending said lines to said trunks, said selector having a brush shaft with brushes therefor, a rotary and a vertical stepping magnet, means for operating the rotary magnet to bring a set of brushes into worhng relation with one of said groups-of contacts, means for menace energizing the vertical magnet, a vertical stepping pawl actuated thereby to step the positioned set of brushes over said group of contacts to search for an idle one thereof, a vertical holding pawl co-acting with the stepping pawl to maintain the brushes in their operated osition, means actuated if no idle trunk is ound to render the stepping and holding pawls inefiective, means operated by the vertical magnet for thereupon assuming control of said brushes to step the same in the opposite direction over the group of contacts, and means efiective while said brushes are moving in either direction for arresting them upon the contacts of the first idle trunk found.

8. In a telephone system, telephone lines, an automatic switch adapted to extend said lines, grou s of trunk terminals in said switch, sai switch including a brush shaft with brushes therefor, a stepping magnet, controllin means actuated by the magnet to step said rushes in one direction over one of said terminal groups, controlling means actuated by said magnet to step the brushes in the opposite direction over the terminal group, and meansactuated when saidbrushes are at either of their extreme positions for shiftin the control of such brushes from one to t lie other of said controlling means.

In witness whereof, I hereunto subscribe myTname this 16th day of August A. D, 191

OLD F D. M. GUll-IE. 

